With the development of the internet, cloud services that combine the server and the internet together have become widely used in recent years, so the amount of the data that the server needs to process grows at a remarkable speed. This causes a high demand for a server having larger storage space and faster write/read speed.
Generally, the server accommodates not only storage units but also components such as a motherboard, a heat dissipating module and expanding cards. Therefore, the conventional servers have a low density of storage unit under such a circumstance.